A valve for a reciprocating compressor is known in the state of the art. Such valve comprises a seat and a guard, which are substantially planar grills facing each other and placed substantially parallel to each other. The seat and the guard both have holes. However, those holes mostly do not overlap.
A shutter element is placed between the seat and the guard. The shutter element is in particular designed so that it can cover the holes on the valve seat. With more detail, the shutter element is pushed against the seat by a set of springs acting between the guard and the shutter element itself. The passage of fluid is thus prevented.
When the pressure from the working fluid increases beyond a predetermined threshold, it can then overcome the elastic force of the springs, thus forcing the valve open and allowing the passage of fluid until the pressure decreases below the acting threshold.
This valve, while being fully automatic (as the opening and closing actions are determined only by the pressure difference between the two sides) disadvantageously precludes the possibility of opening and closing itself on preset conditions other than such pressure difference.
In order to overcome such disadvantage the related art provides other devices, such as the one shown in the document US2012/0260796. This valve, while retaining the basic construction of the state of the art valve, also comprises a valve lifter acting on the shutter element and moved by an electromagnetic linear motor. Such valve lifter can only open the valve, as it relies on the spring for closing it.
Disadvantageously, such valve is exceedingly complex, thus potentially unreliable. Also, this type of valve needs more space inside the cylinder than the fully automatic version.
Document U.S. Pat. No. 6,149,400 describes a suction valve of the plate-type of construction, comprising a valve plate which is actuated by an electromagnet arranged in a valve catcher. Such design however implies having an electric circuit in close proximity to the process gas, which may itself be inflammable or explosive. Therefore, this kind of valve cannot be safely be employed in such cases.